Cardiac Imaging for Coronary Artery Diseaseeradiology.bidmc.harvard.edu/LearningLab/cardio/Malhotra.pdf · Cardiac Imaging for Coronary Artery Disease ... • Fever/Infection

Rajeev Malhotra, HMS IVGillian Lieberman, MD

Cardiac Imaging for Coronary Artery Disease

Rajeev Malhotra, Harvard Medical School Year IVGillian Lieberman, MD

July 2003

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Coronary Artery Disease

• Major cause of morbidity and mortality in the U.S.

• 1.2 million MI’s every year• 600,000 deaths yearly related to CAD• Cardiac cath and echocardiography both top

the list of the amount spent in U.S. health care of all imaging modalities

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Modalities

• Angiography• Nuclear Medicine• Echocardiography• MRI• Conventional CT/Electron beam CT

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Cardiac Catheterization -- Indications

• Angina unresponsive to medical management• Unstable angina• Angina following MI or CABG• Asymptomatic patients with high suspicion of

CAD (e.g., abnormal EKGs or positive stress tests or numerous cardiac risk factors)

• Patients undergoing surgery for valvular dz• LV dysfunction of unclear etiology

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Cardiac Catheterization -- Contraindications

• Bleeding diatheses• Advanced age with poor physiology• Uncontrolled hypertension• Significant electrolyte abnormalities• Fever/Infection• Severe anemia• Active GI bleeding• Recent h/o CVA• Prior contrast reaction• Significant renal failure or anuria

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Right Anterior Oblique

http://info.med.yale.edu/intmed/cardio/imaging/

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RAO


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Left Anterior Oblique


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LAO


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Ventriculogram


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Patient #1: History

• A 49 year old man with 4 hours of chest pain.

• EKG: ST elevation in II, III, aVF, V5 and V6. ST depression in V1 and V2.

• Treatment: aspirin, beta-blockers and thrombolysis.

• Peak CK: 3905, TNI >50

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Patient #1 Sent to cardiac cath lab

BIDMC patient, courtesy Dr. Danias

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Patient #1(cont’d)


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Patient #2: RCA stenosis


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Patient #2: Post-Angioplasty


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Patient #2: post-angioplasty


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Echocardiography

• Regional wall motion abnormalities can be seen within seconds of a coronary artery occlusion (prior to onset of symptoms)

• localized decrease in amplitude and rate of myocardial excursion

• Excellent negative predictive value for chest pain

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Echocardiography

Circulation 1991 Sep;84(3 Suppl):I85-92

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Left Parasternal Long Axis View


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Echo -- Long Axis View

Left parasternal long axis view(http://info.med.yale.edu/intmed/cardio/echo_atlas/views/index.html)

-- Reliable view of the septum and posterior LV wall.

-- Diastolic opening of mitral valve.

-- Systolic opening of the aortic valve

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Short Axis View of the LV


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Short Axis View of the LVView of the ventricular contractile motion, which should be symmetric.

Good view to focus in on septal or inferior wall defects.


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Short Axis View of the Aortic Valve


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Short Axis View of the Aortic Valve

-- “en face” view of the aortic valve leaflets-- LA behind aortic root-- Pulmonary valve opening


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Transesophageal Echo

• High-frequency (5 MHz) ultrasound transducer mounted on the tip of a directable gastroscope-like tube about 12mm in diameter

• Close direct fluid contact with the posterior heart

• Superb images; no interference from lungs

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Transesophageal Echo

http://info.med.yale.edu/intmed/cardio/imaging/techniques/echo_tee/index.html

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Patient #1 with Inferior MI Short axis view useful for detecting akinesis in coronary

distributions

BIDMC patient

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Echo and Valvular Disease


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Echo and Valvular Disease: Aortic Regurgitation


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Cardiac MRI

• Uses high intensity magnetic fields and radiofrequency to generate 3D/tomographic images with high resolution and excellent contrast

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Cardiac MR -- Indications

• Carotid artery disease, risk assessment of emboli

• Coronary anomalies• Aortic aneurysm• Aortic dissection, intramural hematoma• Aortitis• Congenital anomalies

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Cardiac MR – Other Applications

• EF assessment• Valvular disease• Wall motion abnormalities• Coronary MRA

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Cardiac MR -- Techniques• Spin-echo for anatomic imaging obtain single static

pictures in slices; • depicts the tissue structures of the heart as bright and the

blood pool as dark• For assessing myocardial mass and zones of infarction

• Gradient echo for functional imaging obtain cine loops, multiple images at different phases of the cardiac cycle

• the blood pool appears as bright and cardiac tissue structure appears dark

• Used to evaluate ventricular function, valvular lesions, shunts

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Cardiac MR – Coronal Slice


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Return to Patient #1 with Inferior MI


Akinesia of antero and infero-lateral LV wall

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Patient #1: Hyperenhancement seen after Gd-DTPA administration

Diagnosis: Transmural myocardial infarction with a large no reflow zone in the circumflex territory. Confirmed by cath.

BIDMC patient, courtesyDr. Danias

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MRI and CAD

• Provides an accurate, 3-D perspective of the heart, with measurements of EF, volume, and mass

• Ischemic territories can be identified by using IV gadolinium for a first-pass perfusion study

• Dobutamine infusion visualize segments that become ischemic (ie, demonstrate reduced motion) during stress

• Direct assessment of coronary plaques

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Patient #3: 26-year-old asymptomatic female with normal EKG, echo, and CXR. Patient’s mother died suddenly at age 48 with v-fib.

Images courtesy Dr. Danias

•Borderline sized LV with good systolic function (LVEF 68%). •Mildly dilated RV, but with normal function•On spin echo images, regional enhancement of MR signal intensityin a circumscribed area of the free right ventricular wall (not just

coronary fat).

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Patient #3: Arrhythmogenic RV Dysplasia

• Prevalence: 1 in 5000• Is a cause of sudden death in the young• Strong genetic correlation (e.g., prevalent in

southern Italy)• Characterized by ventricular arrhythmias• Fibrofatty replacement of the RV myocardium• Approx. 50% have normal EKG upon discovery• MRI is the tool of choice for diagnosis

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Cardiac MR -- Contraindications

• Pacemaker• Implanted defibrillator• Aneurysm clips• Cochlear implants• Swan-Ganz catheter• History of recent coronary artery stenting (<6wks)• Prosthetic valves are safe except for the Starr-

Edwards ball valves

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Conventional CT and Coronary Artery Calcification (CAC)

• In asymptomatic patients, conventional CT discovered coronary calcification in 29% of men and 19% of women over the age of 40

• Sensitivity: CT showed calcium in 62% of vessels with significant lesions on angiography (Rienmuller er al.)

• 90% of those patients with high calcification detected by CT had significant stenosis on angiography (PPV) (Masuda et al.)

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Conventional CT and CAC

BIDMC PACS

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Limitations of Conventional CT

• Slow scan times, motion artifacts• Volume averaging• Breathing misregistration• Inability to quantify the amount of plaque

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Electron Beam CT

www.vitalimaging.com

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Electron Beam CT

• Traditional CT – uses x-ray tube that revolves around patient. Scan times are on the order of 1 second.

• EBCT – uses an electron beam that focuses on tungsten targets beneath the patient, producing x-rays.

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Electron Beam CT

• Highly sensitive in detecting coronary artery calcifications

• Can be used as a screening tool in asymptomatic patients

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www.vitalimaging.com

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CAC Exam

• Only Noninvasive test to detect early CAD

• Only Noninvasive test to:– Directly Image Coronary Arteries– Quantify Disease Present– Institute Measures to Stop Progression– Monitor Progression

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Agatston Scoring

• Evaluates the area of calcification in sequential images

• Using threshold of 130 HU, a score for each lesion is given:

AREA (in mm2) x CO-FACTOR• Co-factor ranges from 1-4 depending on the HU

peak value of the lesion• Separate scores obtained for left main, LAD, LCx,

and RCA

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Three-vessel-disease

BIDMC PACS, courtesy Dr. Mastromatteo

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Isolated LAD Disease

BIDMC PACS, courtesy Dr. Mastromatteo

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When to use EBCT for CAC?

• 1. In the asymptomatic but high-risk patient to assess need for further testing.

• 2. In evaluating equivocal cardiac screening tests, such as stress EKG.

• 3. In evaluating the patient with chest pain in the ED, where a cardiac origin is much less likely in the absence of CAC.

• 4. In influencing therapeutic decisions in patients with hypercholesterolemia.

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Other Indications for EBCT

• To evaluate bypass graft patency• Congenital cardiac lesions• Quantify ventricular muscle mass, chamber

volumes, and function (CO and EF)

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EBCT

• Advantages• Non-invasive• Quick• Best modality at detecting

calcium in vessels• Could be used as a

screening for CAD (calcium deposition comes well before symptoms arise)

• Disadvantages• It is still unclear how CAC

correlates with risk of significant vessel narrowing

• Does not detect soft plaques.

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EBCT

• EBCT measurement of coronary calcium is of no known value in patients who have already had a heart attack or undergone CABG

• The increased predictive value of EBCT for coronary disease relative to traditional risk factor assessment isn't yet completely defined.

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Acknowledgements

• Dr. Peter Danias• Dr. Michael Mastromatteo• Larry Barbaras our Webmaster• Gillian Lieberman, MD• Pamela Lepkowski• And special thanks to Griffin Weber

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References• BIDMC PACS• Marcus et al., Cardiac Imaging, SYNTEX, 2000.• www.medscape.com• Lecture on Cardiac MR by Dr. Peter Danias, BIDMC, July 2003.• http://info.med.yale.edu/intmed/cardio/imaging/• www.uptodateonline.com• Boxt, LM. “Cardiac Radiology.” The Radiologic Clinics of North

America, March 1999.• www.scmr.org• Reinmuller and Lipton. Detection of CAC by CT. Dynam Card

Imaging 1:139-145, 1987.• Masuda et al. CAC detected by CT. Angiology 41:1037-47, 1990.• www.vitalimaging.com• Circulation 1991 Sep;84(3 Suppl):I85-92


http://www.uptodateonline.com/

http://www.scmr.org/

Documents

Cardiac Imaging for Coronary Artery Diseaseeradiology.bidmc.harvard.edu/LearningLab/cardio/Malhotra.pdf · Cardiac Imaging for Coronary Artery Disease ... • Fever/Infection